Apparatus and method for cable covering

ABSTRACT

Apparatus and method for covering cables with flexible thinwalled tubing for sliding fit, for use in such applications as pre-tensioning or post-tensioning concrete installations. The cable is coated with lubricant, and fed into a length of extended tubing from a nozzle to which the tubing is secured.

[ 1 Sept. 12, 1972 United States Patent Campbell 3,332,138 7/1967Garner........................29/43O [54] APPARATUS AND METHOD FOR CABLECOVERING [72] Inventor:

Primary Examiner-Thomas H. Eager lan Wallace Campbell, 2750 Tudor Ave,Victoria, British Columbia Attorney John Pmthroe Canada [57] ABSTRACTApparatus and method for covering cables with flexi- -walled tubing forsliding fit, for use in such applications as pre-tensioning orpost-tensioning concrete installations. The cable is coated withlubriand fed into a length of extended tubing from a nozzle to which thetubing is secured.

.m m e o 6 3 l W9 2 2 0 2 9 m w m 9 l a m &m ,m m 8 m Mm l c p 0 mp5 FAU U U l 22 5 .B23p 19/00, B23p 19/04 [58] Field of Search..........29/430, 433, 202.5, 241

6 Claims, 5 Drawing Figures [56] References Cited UNITED STATES PATENTS2,876,534 3/1959 Savona........ ............29/241 X APPARATUS ANDMETHOD FOR CABLE COVERING This invention relates to an improved methodand apparatus for covering cables, and more specifically relates to amethod and apparatus for covering multistrand cables with a seamlessflexible thin-walled tubing, where a sliding fit is desirable betweenthe cable and the tubing.

Conventional means for manufacturing covered cable consist of eitherwrapping the cable in a flexible strip covering, wound spirally on thecable, or alternatively, enclosing the cable in a thin, flexible-walledsheathhaving .a longitudinal seam, which is progressively closed as thecable advances through sealing apparatus.

Such method and apparatus as has been heretofore used produces a closecontact between the cable and the covering, so that relative movement ofthe cable within the covering is difficult or impossible in long lengthsof covered cable. Accordingly, where relative movement of the cablewithin the covering is desirable,

such method and apparatus as is hereinabove described has provenunsatisfactory.

Relative movement of the cable within the covering is desirable in manyapplications. For example, in prestressed concrete structural members,where internal compressive forces are induced in the structural memberprior to external loading, such internal compressive forces are normallyinduced by tension loading of longitudinal steel tension rods or cablespositioned within the structural member on the compression side of theneutral axis. Such tension prestressing can be accomplished by eitherpre-tensioning or post-tensioning the longitudinal bars or cables.

Pre-tensioning lends itself only to members that can be precast andreadily transported and precludes the advantages of monolithiccast-in-place construction. Post-tensioning, on the other hand, lendsitself well to monolithic cast-in-place construction.

Post-tensioning consists of imbedding high tensile strength cable,protected by thin-walled covering within which the cable may move, inthe concrete. After the concrete is cast and has reached sufficientstrength, the cable is stressed in tension, normally by means ofhydraulic jacks, and then anchored with nonslip end anchorages securedin the edges or ends of the concrete member.

The cable must be free to move within the covering, otherwise uniformtension will not be developed throughout the length of the tensionmember.

In normal post-tensioning practise, the tension member comprises a sevenwire cable of high carbon steel, forming a one-half inch diameter cablehaving an ultimate strength of approximately 270,000 pounds per squareinch. The cables are coated with a rust-inhibiting, low-viscositygrease, and then encased in flexible polyethylene tubing having a wallthickness of approximately ten mils and an internal diameter ofapproximately five-eighths of an inch.

It is an object therefore, of this invention, to provide an improvedmethod and apparatus for continuously forming a multiple-strand cable,clad in a seamless flexible covering, wherein the cable constitutes aloose sliding fit within the covering.

Another object of the invention is the provision of automatic apparatusfor forming a multiple-strand covered cable having a loose sheath fitand including means for dispensing a lubricant for application upon thecable immediately prior to the introduction of the cable into thecovering.

These and other advantages will become apparent through theconsideration of the following detailed description taken in conjunctionwith the attached drawings to which they relate.

I The apparatus invention consists broadly of the provision of anapparatus comprising storage means for a supply of cable, means forwithdrawing said cable from storage, means for coating the cable with asuitable lubricant, means for feeding the cable into a preformedseamless tube, and means for severing the covered cable so formed intoconvenient lengths.

The method invention in broad aspect comprises a method of coveringflexible cable with tubular cable covering comprising the steps ofcoating the cable with a suitable lubricant, and feeding said cable intothe case of a suitable cable covering having an internal diameterslightly in excess of the external diameter of said cable.

One embodiment of the apparatus of the invention consists of thearrangement and construction of parts all as hereinafter moreparticularly described, reference being had to the accompanying drawingsin which:

FIG. 1 is a general perspective view of the apparatus embodying thepresent invention; 7

FIG. 2 is a longitudinal cross-sectional view through the cablelubricating unit and the cable covering assembly;

FIG. 3 is the top plan view of the cable covering as sembly;

FIG. 4 is an end elevational view of the cable covering assembly takenalong the line 44 of FIG. 2;

FIG. 5 is a detail of the cable feeding nozzle.

In the drawings, like characters of reference indicate correspondingparts in the several figures.

Proceeding, therefore, to describe the invention in detail and referringto the accompanying drawings, in FIG. 1 a cable covering apparatusdesignated generally 10 will be understood to comprise a cable storageassembly 11, a cable transfer assembly 12, a cable lubricating assembly13, a cable covering assembly 14, and a cable covering trough assembly15. These various major assemblies are maintained in general alignmentwith one another on a common supporting floor. The cable storageassembly 11 comprises desirably a spool or drum 16, supported axiallyhorizontally by means of the shaft 17, supported for journalled rotationin the support members 18 as is clearly depicted in FIG. 1.

The cable transfer assembly 12 consists of a supporting frameworkgenerally designated 19, comprising the floor-engaging legs 20, a pairof intermediate longitudinal support members 21, a plurality of upperlongitudinal support members 22 and an upper transverse support member23. The framework may be conveniently constructed of steel anglemembers, desirably welded together at their connections.

A train of roller guides, mounted in two mutually vertically disposedsets, and cooperating to receive and advance the cable from the coveringstorage assembly, is positioned within the supporting framework 19. The

lower set of roller guides 24 comprises a plurality of identical sheaves25, each having a half-round peripheral groove therein, mounted forhorizontal axial rotation in mutual longitudinal alignment as depictedin FIG. 1. Each of the sheaves 25 is supported on a horizontal shaft 26,keyed to a sprocket 27. An electric motor drive 28, and chain assemblygenerally designated 29 engages the sprockets 27 in a positive drive,each of the sheaves 25 rotating with the same peripheral velocity.

The upper set of roller guides 30 comprises a like number of sheaves,journally mounted immediately above and in alignment with the set ofdriving roller guides 24, asdepicted in FIG. 1. These guides are adaptedfor idler rotation from contact with the cable and the driven guides 24,and are designed to receive and maintain contact between the cablesupply and the driving roller guides 24. 7

Each of the idler guides 30 is journalled for rotation in spring mountedbearings 31, biased downwardly, thereby maintaining pressure contact ofthe cable supply against the driving guides 25.

The cable lubricating assembly 13 essentially comprises a lubricantstorage tank 32, mounted in general alignment with the cable feedingassembly 12 upon the support framework 19, and being adapted to receivethe cable after it has passed between the roller guides 24 and 30. Acable inlet opening 33 and a cable outlet opening 34, with nozzleinserts 33' and 34 respectively, each in axial alignment with the rollerguides 24 and 30 provide entry and exit means to and from the cablelubricating unit 13. The nozzle inserts are desirably removable forreplacement after wear; nozzle insert 33 is constructed preferably ofrelatively resilient plastic such as nylon, while nozzle 34' isconstructed preferably of a wear-resistant metal such as ni-chromesteel.

The cable covering assembly generally designated 14, comprises the cablefeeding nozzle 34, adapted to receive in overlaying fashion the butt endof the cable cable cover 35 to be securely held on the cable feedingnozzle 34 during the operation of the apparatus, and subsequent rapidrelease.

The cable cover trough assembly 15 mounted adjacent and in general axialalignment with the cable feeding assembly 12, supports initially alength of cable cover 35 in extended fashion as depicted in FIG. 1, andat the conclusion of the operation supports the lengthy covered cable.

In operation, the free end of the cable 37 is uncoiled from the cablestorage assembly 11, and fed into the cable feeding assembly 12 from theentry roller guide 38, and is threaded between the adjacent pairs ofroller guides 24 and 30. The free end of the cable is delivered by thedriving guides 25 through the cable entry opening 33 into the cablelubricating unit 13, where it is passed through and acquires a coatingof suitable lubricating grease 38. The free end of the cable 37 is thendirected to the cable feeding nozzle 34' and the butt end of the cablecover 35 is positioned over the cable feeding nozzle 34 where it issecured by means of the cable cover clamp 36. Operation of the motordriven guide trains 25, through friction contact with the cable 37,forces the cable upon discharge through the bore of the cable cover 35,and outwardly into the cable trough assembly 15. When a satisfactorylength of covered cable has been produced, the operation isdiscontinued, and the covered cable is severed adjacent the nozzle 14,by any convenient cutting means such as shears or cutting torch (notillustrated).

Since various modifications can be made to the invention hereindescribed within the scope of the inventive concept disclosed, it is notintended that protection of the said invention should be interpreted asrestricted to the particular modifications or known parts of suchconcept as particularly described, defined or exemplified, since thisdisclosure is intended to explain the construction and operation of suchconcept and is not for the purpose of limiting protection to anyspecific embodiment or detail thereof;

Whatl claim as my invention is:

1. Apparatus for cable covering for use with flexible cable and tubularcable covering comprising, in combination: cable storage means; a cabletransfer assembly; cable lubricating means; a cable feeding nozzle;means for securing an end of said cable covering to said nozzle; andmeans to support said tubular cable covering in substantially extendedcondition for passage therethrough of said flexible cable upon dischargethereof from said cable feeding nozzle.

2. Apparatus according to claim 1 wherein said cable transfer assemblycomprises a [plurality of rotating roller guides in mutually opposedrelationship and a power source driving at least one of said rollerguides.

3. Apparatus for cable covering for use with flexible cable and tubularcable covering comprising, in combination; cable storage means; aplurality of roller guides in opposed paired arrangement; at least oneof the adjacent members of each of the said pairs being inwardly springbiased; a power source driving at least one of said roller guides; cablelubricating means comprising a lubricating tank mounted adjacent to saidroller guides; an inlet nozzle mounted upon one wall of said lubricatingtank and a cable feeding nozzle mounted upon the opposite wall of saidlubricating tank, each of said nozzles being in axial alignment withsaid roller guides and being adapted respectively to introduce anddischarge flexible cable from said lubricating tank; means for securingan end of said tubular cable covering to said discharge nozzle; andmeans to support said tubular cable covering in substantially extendedcondition for passage therethrough of said flexible cable upon dischargethereof from said discharge nozzle.

4. Apparatus for cable covering for use with flexible cable and tubularcable covering comprising, in combination: cable storage means; cabletransfer means comprising a plurality of roller guides in opposed pairedarrangement, at least one of the adjacent members of each of said pairsbeing inwardly spring biased; a framework for supporting said rollerguides; a power source driving at least one of said roller guides; cablelubricating means comprising a lubricating tank mounted adjacent to saidroller guides; an inlet nozzle mounted upon said lubricating tank and adischarge nozzle mounted upon said lubricating tank opposite said inletnozzle, each of said nozzles being in axial alignment with said rollerguides and being adapted respectively to introduce and dischargeflexible cable into and from said lubricatingtank; means for securing anend of said tubular cable covering to said discharge nozzle; and meansto support said tubular cable covering in substantially extendedcondition for passage therethrough of said flexible cable upon dischargethereof from said discharge nozzle.

5. Apparatus for cable covering for use with flexible cable and tubularcable covering comprising in combination: cable storage means; arectilinear ground-engaging framework; cable transfer means comprising aplurality of roller guides in opposed paired arrangement mounted forrotation upon 'said framework, at least one of the adjacent members ofeach of said pairs of roller guides being inwardly spring-biased; apower source driving at least one of said roller guides; cablelubricating means comprising a lubricating tank mounted adjacent to saidroller guides; and inlet nozzle mounted upon said lubricating tank and adischarge nozzle mounted upon said lubricating tank opposite said inletnozzle, each of said nozzles being in axial covering having an internalbore of a diameter slightly in excess of the external diameter of saidflexible cable and having a length at least substantially equivalent tothe length of said cable; coating said cable with a suitable lubricant;securing an end of said tubular cable covering and introducing saidcable with said associated lubricant coating into the internal bore ofsaid tubular cable covering so that said cable is substantially fullycovered by said cable covering. 4

1. Apparatus for cable covering for use with flexible cable and tubularcable covering comprising, in combination: cable storage means; a cabletransfer assembly; cable lubricating means; a cable feeding nozzle;means for securing an end of said cable covering to said nozzle; andmeans to support said tubular cable covering in substantially extendedcondition for passage therethrough of said flexible cable upon dischargethereof from said cable feeding nozzle.
 2. Apparatus according to claim1 wherein said cable transfer assembly comprises a plurality of rotatingroller guides in mUtually opposed relationship and a power sourcedriving at least one of said roller guides.
 3. Apparatus for cablecovering for use with flexible cable and tubular cable coveringcomprising, in combination; cable storage means; a plurality of rollerguides in opposed paired arrangement; at least one of the adjacentmembers of each of the said pairs being inwardly spring biased; a powersource driving at least one of said roller guides; cable lubricatingmeans comprising a lubricating tank mounted adjacent to said rollerguides; an inlet nozzle mounted upon one wall of said lubricating tankand a cable feeding nozzle mounted upon the opposite wall of saidlubricating tank, each of said nozzles being in axial alignment withsaid roller guides and being adapted respectively to introduce anddischarge flexible cable from said lubricating tank; means for securingan end of said tubular cable covering to said discharge nozzle; andmeans to support said tubular cable covering in substantially extendedcondition for passage therethrough of said flexible cable upon dischargethereof from said discharge nozzle.
 4. Apparatus for cable covering foruse with flexible cable and tubular cable covering comprising, incombination: cable storage means; cable transfer means comprising aplurality of roller guides in opposed paired arrangement, at least oneof the adjacent members of each of said pairs being inwardly springbiased; a framework for supporting said roller guides; a power sourcedriving at least one of said roller guides; cable lubricating meanscomprising a lubricating tank mounted adjacent to said roller guides; aninlet nozzle mounted upon said lubricating tank and a discharge nozzlemounted upon said lubricating tank opposite said inlet nozzle, each ofsaid nozzles being in axial alignment with said roller guides and beingadapted respectively to introduce and discharge flexible cable into andfrom said lubricating tank; means for securing an end of said tubularcable covering to said discharge nozzle; and means to support saidtubular cable covering in substantially extended condition for passagetherethrough of said flexible cable upon discharge thereof from saiddischarge nozzle.
 5. Apparatus for cable covering for use with flexiblecable and tubular cable covering comprising in combination: cablestorage means; a rectilinear ground-engaging framework; cable transfermeans comprising a plurality of roller guides in opposed pairedarrangement mounted for rotation upon said framework, at least one ofthe adjacent members of each of said pairs of roller guides beinginwardly spring-biased; a power source driving at least one of saidroller guides; cable lubricating means comprising a lubricating tankmounted adjacent to said roller guides; and inlet nozzle mounted uponsaid lubricating tank and a discharge nozzle mounted upon saidlubricating tank opposite said inlet nozzle, each of said nozzles beingin axial alignment with said roller guides and being adaptedrespectively to introduce and discharge flexible cable from saidlubricating tank; means for securing an end of said tubular cablecovering to said discharge nozzle; and means to support said tubularcable covering in substantially extended condition for passagetherethrough of said flexible cable upon discharge thereof from saiddischarge nozzle.
 6. The method of covering flexible cable with tubularcable covering comprising the steps of: providing a length of flexiblecable and a length of tubular cable covering having an internal bore ofa diameter slightly in excess of the external diameter of said flexiblecable and having a length at least substantially equivalent to thelength of said cable; coating said cable with a suitable lubricant;securing an end of said tubular cable covering and introducing saidcable with said associated lubricant coating into the internal bore ofsaid tubular cable covering so that said cable is substantially fullycovered by said cable covering.